Aircraft Accident/Incident Report

Salt Lake City, Utah 84122
Monday, December 6, 1999 16:55 MST

NTSB Narrative Summary Released at Completion of Accident

The crew heard a loud noise and felt a vibration when the landing gear was retracted after takeoff. An emergency was declared, and the flight returned to Salt Lake City. When the landing gear was lowered, the nose and right main landing gear DOWN AND LOCKED lights illuminated, but a GEAR UNSAFE light illuminated for the left main landing gear. Following a low pass over the airport, maintenance personnel advised the landing gear appeared to be down and locked. An uneventful landing was made. Maintenance personnel informed the crew that the landing gear actuator had sheared and could not be pinned for towing. The part was later removed and examined. Stress corrosion cracking had occurred through 75% of the piston, followed by ductile separation. The corrosion had formed when a faulty fillet seal around the base of the rod end allowed moisture to enter the joint. The retract actuator was an original part, but it was determined that it had previously been reworked.

NTSB Probable Cause Narrative

Total failure of the main landing gear retract actuator due to stress corrosion caused by the use of a faulty sealant by company maintenance personnel that allowed moisture to enter the joint. A factor was the use of an improper fillet seal.

Event Information

Type of Event Incident
Event Date 12/6/1999
Event Day of the Week Monday
Time of Event 1655
Event Time Zone Mountain Standard Time
Event City SALT LAKE CITY
Event State UTAH
Event Country --
Zipcode of the event site 84122
Event Date Year 1999
Event Date Month 12
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude
Event Location Longitude
Event Location Airport
Event Location Nearest Airport ID
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness Not pertinent
Investigator's weather source Weather Observation Facility
Time of the weather observation 1700 Mountain Standard Time
Direction of event from weather observation facility (degrees) 0
Weather Observation Facility ID SLC
Elevation of weather observation facility 4227
Distance of event from weather observation facility (units?) 0
Time Zone of the weather observation MST
Lighting Conditions Day
Lowest Ceiling Height 7000
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Unknown
Sky Condition for Lowest Ceiling Broken
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 8
Air Temperature at event time (in degrees celsius) 2
Dew Point at event time (in degress fahrenheit) -3
Wind Direction (degrees magnetic) 290
Variable Wind Indicator Unknown
Wind Speed (knots) 4
Wind Velocity Indicator Unknown
Wind Gust Indicator Not Gusting
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 30
Density Altitude (feet) 3551
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor --
Injury Total None 85
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 10399
NTSB Notification Source --
NTSB Notification Date Dec 7 1999 12:00AM
NTSB Notification Time 730
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Aug 13 2001 9:42AM
User who most recently changed record MONR
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N111DN
NTSB Number DEN00IA023
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 121: Air Carrier
Type of Flight Plan filed IFR
Flight plan Was Activated? --
Damage Minor
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Boeing
Aircraft Model 767-232
Aircraft Series Identifier 767-232
Aircraft Serial Number 22223
Certified Max Gross Weight 300000
Aircraft Category Airplane
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 217
Number of Engines 2
Fixed gear or retractable gear Retractable
Aircraft, Type of Last Inspection Continuous Airworthiness
Date of Last Inspection Dec 4 1999 12:00AM
Airframe hours since last inspection --
Airframe Hours 51977
ELT Installed No
ELT Activated Unknown
ELT Aided Location of Event Site Unknown
ELT Type --
Aircraft Owner Name DELTA AIR LINES, INC.
Aircraft Owner Street Address 1020 DELTA BLVD., DEPT. 023
Aircraft Owner City ATLANTA
Aircraft Owner State GA
Aircraft Owner Country
Aircraft Owner Zipcode 30320
Operator is an individual? --
Operator Name
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address 1775 AVIATION BLVD.
Operator City ATLANTA
Operator State GA
Operator Country
Operator Zip code 30320
Operator Code DALA
Owner has at least one certificate Yes - certificate holder
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not Scheduled
Indicates Domestic or International Flight Domestic
Operator carrying Pax/Cargo/Mail Passenger Only
Type of Flying (Per_Bus / Primary) Unknown
Second Pilot on Board Yes
Departure Point Same as Event Yes
Departure Airport Code SLC
Departure City
Departure State
Departure Country
Departure Time 1655
Departure Time Zone MST
Destination Same as Local Flt --
Destination Airport Code DFW
Destination City DALLAS-FT WORTH
Destination State TX
Destination Country
Specific Phase of Flight Takeoff
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Dec 20 2002 12:42PM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --